Re: FYI, B757 crash at Bermuda.

From:         "Rudi Vavra" <flying@oznet02.ozemail.com.au>
Organization: Goodfox Pty. Ltd.
Date:         07 Jul 96 14:15:54 
References:   1 2 3
Followups:    1
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Brian A. Reynolds wrote:

> 9)	A stall is caused by disrution of airflow over the wings.  If
>  the aircraft's nose is excessively high, the airflow will be
>  disrupted.  The angle of attack (the angle of the aircraft
>  centerline relative to actual direction of travel) is deteced by
>  an Angle-of-Attack sensor (AOA for short) which is a vane like
>  device which 'flies' in the airstream.  If airspeed is sufficient,
>  then the AOA will stay within limits.  If the angle of attack
>  vs airspeed is insufficient, then the AOA (as measured by the
>  sensor) will be come excessive and generate a stall warning.

WRONG! The AOA is the angle between the chord of the wing and
the relative airflow. The AOA can be exceeded at ANY airspeed and the
airplane will STALL at ANY airspeed once a critical AOA has been
exceeded. This is important. You CAN stall an airplane at any
airspeed.

> 12)	The flight crew experienced simultaneous stall and overspeed
>  indications.  In reacting to the overspeed warning, the nose
>  was pitched up to decrease the airspeed.  This increased the
>  angle of attack, deepening the stall.
> 13)	At some point the aircraft ceased to have sufficient airflow
> over
>  the wings and stopped flying.

The aircraft stopped flying AS SOON AS it stalled. It doesn't matter
how deep the stall is, after you stall a wing, lift drops
dramatically. The plane was probably kept in a stall
unintentionally, as the overspeed warning was still sounding. Usually
if you stall an airplane and hold it in a stall, it will drop one
wing quite suddenly and dramatically. In all probability, the
airliner went inverted, or close to it after it stalled.Obviously
there was not enough time and not enough altitude to recover from
this unusual attitude in this case.

All the above is pure speculation based on my aeronautical knowledge.
I'll wait for the official findings in this case.

Rudi


--
Rudi Vavra <flying@ozemail.com.au>
http://www.ozemail.com.au/~flying
(Those Magnificent Men and Their Flying Machines)
--
<<The beatings will continue until morale improves.>>